Carcinoma

Carcinoma is a type of cancer that begins in epithelial cells. Epithelial cells are specialized cells that line the surfaces of your body, both inside and out. For example, epithelial cells form your skin, line your digestive tract, and cover the surfaces of organs like your lungs, breasts, and prostate. Carcinomas can start in any part of your body where epithelial cells are found, making them the most common type of cancer.

Types of carcinoma

There are several different types of carcinoma. Each type is named based on how the cancer cells look under a microscope and the kind of epithelial cells from which they arise.

The most common types include:

• Squamous cell carcinoma: This carcinoma is made up of abnormal squamous cells, which are flat cells normally found on the surface of the skin and in tissues lining the mouth, throat, esophagus, lungs, and cervix. Squamous cell carcinomas commonly occur in the skin, lungs, oral cavity, and cervix.

• Adenocarcinoma: Adenocarcinoma arises from glandular epithelial cells, which produce fluids such as mucus and digestive juices. It commonly develops in organs such as the colon, stomach, lungs, pancreas, prostate, uterus (endometrium), ovaries, and breasts.

• Neuroendocrine carcinoma: Neuroendocrine carcinomas are cancers made up of specialized  neuroendocrine cells. These cells have characteristics of both hormone-producing (endocrine) cells and epithelial cells. Neuroendocrine carcinomas most commonly arise in the lungs, digestive tract (like the stomach, pancreas, and intestines), and the skin.

What causes carcinoma?

The cause of carcinoma depends mainly on the type and location in the body. Some examples include:

• Lung carcinomas: Many lung carcinomas (especially squamous cell carcinomas and adenocarcinomas) are caused by smoking or exposure to certain environmental toxins.

• Skin carcinomas: Squamous cell carcinomas of the skin typically result from damage due to ultraviolet (UV) radiation from the sun.

• Cervical carcinomas: Most squamous cell carcinomas of the cervix are caused by persistent infection with the human papillomavirus (HPV).

• Colon carcinomas: Adenocarcinomas of the colon are often linked to factors like diet, genetic predisposition, and chronic inflammation.

In many cases, carcinoma development is influenced by a combination of genetic factors, lifestyle choices, infections, and environmental exposures.

How aggressive is carcinoma?

The aggressiveness of a carcinoma depends on many factors, including the specific type, location, size, and stage of the tumor, as well as its microscopic features. Some carcinomas, like specific skin or thyroid cancers, grow slowly and are less likely to metastasize (spread). Other carcinomas, such as certain types of lung or pancreatic cancer, can grow rapidly and spread quickly to different parts of the body. Pathologists carefully examine carcinoma samples to determine how aggressive a tumor is likely to be, and this helps guide treatment decisions.

Are all cancers carcinomas?

No, carcinoma is just one type of cancer. While carcinomas are very common, other types of cancers originate from different kinds of cells. For example:

• Sarcoma: Cancer arising from connective tissues such as bone, muscle, fat, or cartilage.

• Lymphoma: Cancer developing from immune system cells called lymphocytes.

• Melanoma: Cancer that originates from melanocytes, cells that produce pigment in the skin.

Distinguishing carcinomas from other cancer types is important because each cancer type has different treatments and outcomes.